As a heat-resistant photosensitive material, a photosensitive polyimide is widely used in insulating films for semiconductors, passivation films and the like, but it has various problems.
For example, Japanese Patent Application Laid-open No. 54-145794 has suggested a method for mixing a compound containing a double bond and an amino group or its quaternary salt with a polyamic acid. However, since a large amount of the compound containing the amino group or its quaternary salt is added to the unstable polyamic acid solution, there is a drawback that the viscosity of the solution increases with time. Japanese Patent Application Laid-open Nos. 55-45746 and 60-100143 have suggested a method for involving reacting an unsaturated epoxy compound or an isocyanate compound having a double bond with the carboxyl group of a polyamic acid, but this method has a drawback that when the photosensitive unsaturated group-containing compound is reacted with the carboxyl group of the polyamic acid, a part of the polyamic acid decomposes, so that the viscosity of the solution changes. In Japanese Patent Publication No. 55-41422, there has been suggested a polymer in which an active functional group such as a double bond is introduced into the ester side chain of the polyamic acid, but when an acid chloride is reacted with diamine, a chloride remains as an impurity and the removal of this impurity is troublesome. Furthermore, Japanese Patent Application Laid-open No. 60-6729 has suggested a method in which a diamine having a double bond is first synthesized and a polyimide is then synthesized by the use of this diamine, but the process of introducing a photosensitive functional group is complex and a considerable cost is taken.
U.S. Pat. No. 4,093,461 has reported a positive type heat-resistant resist obtained by adding a quinonediazide compound to a polyamic acid, but this resist has a disadvantage that the solubility of the polyamic acid in an alkali is too high, so that film loss is noticeable at the time of development and resolution is poor. U.S. Pat. No. 4,395,482 has reported a positive type heat-resistant resist obtained by adding a quinonediazide compound to a polyoxazole precursor synthesized from a diamine containing a hydroxyl group and a polycarboxylic acid, and Japanese Patent Application Laid-open No. 64-60630 has reported a positive type heat-resistant resist obtained by adding a quinonediazide compound to a polyamidoimide synthesized from a diamine containing a hydroxyl group and tetracarboxylic dianhydride. However, the hydroxyl group-containing diamine has a strong absorption in an ultraviolet region, so that the resist has a drawback that sensitivity is poor.
As is apparent from the foregoing, the conventional techniques have various problems, and thus it is desired to develop a photosensitive material by which such problems can be solved.